One-loop N=8 supergravity coefficients from N=4 super Yang-Mills

TL;DR

This paper derives new formulas for one-loop supergravity scattering coefficients by expressing them as sums of squared Yang-Mills amplitudes, leveraging supersymmetric unitarity methods.

Contribution

It introduces a novel approach to compute N=8 supergravity coefficients using N=4 super Yang-Mills amplitudes, revealing structural insights and simplifying calculations.

Findings

Derived new expressions for all one-loop box coefficients in N=8 supergravity.

Validated formulas against known results in multiple cases.

Connected supergravity coefficients to squared Yang-Mills amplitudes.

Abstract

We use supersymmetric generalised unitarity to calculate supercoefficients of box functions in the expansion of scattering amplitudes in N=8 supergravity at one loop. Recent advances have presented tree-level amplitudes in N=8 supergravity in terms of sums of terms containing squares of colour-ordered Yang-Mills superamplitudes. We develop the consequences of these results for the structure of one-loop supercoefficients, recasting them as sums of squares of N=4 Yang-Mills expressions with certain coefficients inherited from the tree-level superamplitudes. This provides new expressions for all one-loop box coefficients in N=8 supergravity, which we check against known results in a number of cases.